Photoluminescence from metastable states in long-range ordered (Al0.5Ga0.5

Abstract

We have investigated photoluminescence of long-range ordered ͑Al 0.5 Ga 0.5 ͒ 0.51 In 0.49 P grown by metalorganic vapor-phase epitaxy on GaAs͑001͒ and GaAs͑115͒A. Photoluminescence spectra were measured as functions of temperature and delay time. The fundamental edge luminescence from ͑Al 0.5 Ga 0.5 ͒ 0.51 In 0.49 P on GaAs͑001͒ shifts to the lower-energy side about 120 meV at 11 K due to the long-range ordering, relative to the luminescence from the ⌫ conduction-band valley in the disordered alloy. The ⌫ luminescence of ͑Al 0.5 Ga 0.5 ͒ 0.51 In 0.49 P appears at lower energy than the indirect luminescence from the X valley. These observations give clear evidence that the ordering causes the band gap to change from indirect to direct. In the temperature dependence of the photoluminescence ͑PL͒ peak energy, there are three regions divided by a local minimum and a local maximum. Below the temperature showing the local minimum, the temperature dependence of the PL intensity is characteristic of the localization of photoexcited carriers. The origin of the localization is the band-gap fluctuation. The temperature dependence of the PL intensity shows thermal activation between the temperatures showing the local minimum and the local maximum in the PL energy. The activation energy is proportional to the energy shift at the local minimum. In time-resolved PL measurements at low temperatures, we observed a delayed emission due to the electrons trapped at metastable states. The delayed component was only observed below 15 K and the delay time varies with temperature. ͓S0163-1829͑97͒12107-5͔

Photoluminescence on ordered GaxIn1−xAsyP1−y

“…[11][12][13] This effect was also found recently for ͑AlGa͒InP. 14 In contrast to the numerous investigations into the ternary ͑GaIn͒P there are only a few reports on the quaternary ͑GaIn͒͑AsP͒ matched to GaAs. [15][16][17][18][19][20] Indeed, the existence of ordering in MOVPE grown ͑GaIn͒͑AsP͒ matched to GaAs was confirmed by x-ray and transmission electron diffraction.…”

Effects of ordering and alloy phase separation on the optical emission characteristics of In1−xGaxAsyP1−y layers grown on GaAs substrates

“…The existence of both ordering and phase separation in the investigated samples result in a inhomogeneous potential fluctuation in the real space. 13,14 This hypothesis is consistent with the obtained x-ray results shown in Fig. 1, where the relative large x-ray FWHM values obtained for the three investigated samples were attributed to a spatial distribution of domains with different size and ordering degree.…”

Dynamics of Anomalous Temperature-Induced Emission Shift in MOCVD-grown (Al, In)GaN Thin Films

“…A similar anomalous temperature dependence for the PL peak energy was reported for ordered (Al)GaInP [18,19] and disordered (Ga)AlAs/GaAs superlattices [20,21]. Moreover, there have been some reports on the long-range ordering effect in molecular beam epitaxy-grown InGaN and AlGaN films [22].…”